This invention relates to a novel method for the preparation of epoxyalcohols. More particularly, this invention is directed to the oxidation of acyclic or cyclic olefins to form the corresponding epoxyalcohols in the presence of an ion-exchanged bimetallic catalyst in which the metals are valence-bonded to an anionic support.
Use of the aforedescribed catalyst in the process of this invention is particularly advantageous in that no cocatalysts and/or hydroperoxide initiators need be employed, thereby providing an economical, soluble system which requires only relatively low concentrations of catalyst to be effective.
The epoxyalcohols of this invention can easily be converted into diols by hydrogenation (equation 1), and into triols (equation 2) by hydrolysis. ##STR1##
Both diols and triols are well known commercial products. These materials have found utility in the antifreeze market, in the preparation of alkyd resins, new synthetic fibers, synthetic polyester rubbers, solvents, humectants, lubricants and explosives (Mellan, "Polyhydric Alcohols", McGregor and Werner, Washington, D.C 1962).
The utility of the epoxy alcohol derived from cyclohexene has been disclosed in co-pending application, Ser. No. 457,045, filed April 1, 1974, namely, in the production of catechol and resorcinol. A specific utility for the epoxy alcohol derived from tetramethylethylene is the production of pinacol vial hydrogenation: ##STR2##
Pinacol is a useful monomer, being converted by heat and pressure into dimethylbutadiene which forms synthetic rubber when polymerized. (Mellan, "Polyhydric Alcohols"), (supra). 1,3-butane diol and 2,3-butanediol are commercial solvents having high volume utility and may be derived from 1-methyl-1-hydroxy-1,2-epoxypropane: ##STR3## Hexylene glycol is another useful commercial solvent which would be formed by hydrogenation of 2-methyl-2-hydroxy-3,4-epoxypentane an epoxyalcohol derived from 1-methylpentene-2: ##STR4##
All the epoxyalcohols prepared in the examples can be converted to triols. Triols are generally usely as plasticizers and in the manufacturing of alkyd resins and in adhesives. Such diverse triols as 1,2,6-hexanetriol and tetramethylolpropene are effective in all three applications.
In addition, pyrogallol is a commercial product used as an inhibitor and in other applications pyrogallol can be prepared from the epoxyalcohol via the following equation: ##STR5##
Cyclic olefins, such as cyclohexene, when converted to the corresponding 1,2-epoxy-3-hydroxy-cyclohexane, may be dehydrogenated to form catechol. Substituted cyclohexenes yield the corresponding epoxyalcohols which can be dehydrogenated to yeild substituted dihydroxybenzenes.
This invention also relates to certain novel metal-exchanged catalyst per se which are useful in the aforedescribed epoxidation process.
Van Sickle et al, J. Catal. 19, 209 (1970), disclosed the use of cobalt-exchanged zeolites as catalysts for the unselective oxidation of olefins to form a mixture of ketones and unsaturated alcohols, along with a minor amount of epoxides in some cases. U.S. Pat. No. 3,641,066 (1972) teaches a similar process wherein molybdenum, tungsten, or vanadium-exchanged zeolite catalysts are employed in the formation of olefin epoxides. In neither case, however, are epoxy-alcohols obtained as reaction products. Finally, Belgian Pat. No. 640,204 and U.S. Pat. No. 3,259,638 teach the preparation of epoxyalcohols from olefins using as a catalyst system a compound derived from metals of Group IVA, VA, or VIA of the Periodic System, plus an alkylhydroperoxide and a radical initiator.